Connecting signals coming from widgets in a QVector - qt

Question

I'm working on the following Window with QT:
For my rows i have the following structure:
typedef struct
{
struct{
int x;
int y;
int width;
int height;
int layer;
int idx;
}outputSettings;
QDoubleSpinBox *xSpinBox;
QDoubleSpinBox *ySpinBox;
QDoubleSpinBox *heightSpinBox;
QDoubleSpinBox *widthSpinBox;
QDoubleSpinBox *layerSpinBox;
// Checkboxes
QCheckBox *channelCheckBox;
}myUI;
QVector<myUI> inputBoxes; // Create a row of input boxes per channel
I then create them in a for loop:
for(i = 0; i < inputChannels; ++i)
{
inputBoxes[i].channelCheckBox = new QCheckBox;
inputBoxes[i].channelCheckBox->setChecked(true);
inputBoxes[i].xSpinBox = new QDoubleSpinBox;
inputBoxes[i].xSpinBox->setRange(minXPos, maxXPos);
inputBoxes[i].xSpinBox->setSingleStep(1);
inputBoxes[i].xSpinBox->setValue(0);
inputBoxes[i].xSpinBox->setDecimals(0);
connect(inputBoxes[i].xSpinBox, SIGNAL(valueChanged(double)), this, SLOT(setXValue(double)));
inputBoxes[i].ySpinBox = new QDoubleSpinBox;
inputBoxes[i].ySpinBox->setRange(minYPos, maxYPos);
inputBoxes[i].ySpinBox->setSingleStep(1);
inputBoxes[i].ySpinBox->setValue(0);
inputBoxes[i].ySpinBox->setDecimals(0);
connect(inputBoxes[i].ySpinBox, SIGNAL(valueChanged(double)), this, SLOT(setYValue(double)));
...
Now i get stuck on the connect. I want to connect the valueChanged property of my spinboxes to my outputSettings struct. This struct will be my return type at the end.
I implemented the following slots:
public slots:
void setXValue(double x){inputBoxes[0].outputSettings.x = int(x);}
void setYValue(double y){inputBoxes[0].outputSettings.y = int(y);}
...
But here i don't know what vector item called the function. (currently i just entered inputBoxes[0] as a dummy)
My first idea was to add an extra parameter int channel. But then the connect doesn't work. So i tried to work around that with QMapper. But that doesn't seem to be a good option to me and i didn't really get it running.
I would largely appreciate if someone could help me out here or at least point me in the right direction.
Cheers.

Answer 1

Implement it by using a lambda function in your connect
connect(inputBoxes[i], static_cast<void (QDoubleSpinBox::*)(double)>(&QDoubleSpinBox::valueChanged),
[i](double value)
{
// use i as your vector index here
handleDoubleSpinBoxChanged(i, value);
});
Then you can change your slot function to
void handleDoubleSpinBoxChanged(int i, double value)
{
inputBoxes[i].outputSettings.x = int(x);
}
Second option is to get the spin box index from the sender object
you will have to store it first inside your loop
inputBoxes[i].xSpinBox->setProperty("index",i);
Then you can get it
void MainWindow::setXValue(double d)
{
QDoubleSpinBox * sb = qobject_cast<QDoubleSpinBox *>(QObject::sender());
int iCallerVectorIndex = -1;
if (sb != Q_NULLPTR)
{
iCallerVectorIndex = sb->property("index").toInt(); // to get the caller index.
}
}

Answer 2

If I got you right, in your SLOT method you can call sender() to retrieve the object who emitted the signal. You can compare in a loop the spinBoxes of each of your inputBoxes to find out what caused the SLOT to execute, something like:
// in your SLOT method:
for (int i = 0; i < inputChannels; i++){
if (inputBoxes[i].xSpinBox == (QDoubleSpinBox *)sender()){
// the xSpinBox of the i-th inputBox emitted the signal
break();
}
}

Answer 3

You can also just make myUI a QObject and add slot function there.
You wouldnt need any indexes then.
typedef struct
{
Q_OBJECT
struct{
int x;
int y;
int width;
int height;
int layer;
int idx;
}outputSettings;
QDoubleSpinBox *xSpinBox;
QDoubleSpinBox *ySpinBox;
QDoubleSpinBox *heightSpinBox;
QDoubleSpinBox *widthSpinBox;
QDoubleSpinBox *layerSpinBox;
// Checkboxes
QCheckBox *channelCheckBox;
public slots:
setXValue(double);
setYValue(double);
}myUI;
Example of connect call:
connect(inputBoxes[i].ySpinBox, SIGNAL(valueChanged(double)), inputBoxes[i], SLOT(setYValue(double))
or you can call connect in constructor of myUI:
myUI() {
connect(xSpinBox, SIGNAL(valueChanged(double)),
this, SLOT(setXValue(double))
connect(ySpinBox, SIGNAL(valueChanged(double)),
this, SLOT(setYValue(double))
}
I think that would be much simpler and intuitive because your object is responsible to setting his own members and you dont need to remember any indexes.